On Aug 31, 2010, at 7:37 AM, Michael Dickens wrote:
Does any project beyond GNU Radio's USRP actually -require- the
"libusb-legacy" (0.1.12) port / library?
The reason I'm asking is that I want to rename the installed "libusb-
legacy" libraries from "libusb.dylib" (etc) to "libusb-
legacy.dylib" (etc) in order to avoid the (as I'm calling it) "same
name different directory" library linking issue described below
[*]. I've verified that this renaming is relatively simple to
implement via REINPLACE patches to the "libusb-legacy" code, and
that it does indeed resolve the "same name different directory"
issue (because, well, the libraries no longer have the same name :).
NOTES
---
1) There is a "libusb-compat" version that is API compatible (not
ABI compatible, which is why USRP requires the legacy version),
which almost all of the MacPorts ports have been moved to using. In
a search of all current MacPorts Portfiles, I find that libmtp (and,
Amarok via that) has this library requirement, but those ports can
use libusb-compat -- so, I'm updating the Portfiles to reflect this
change. Hence, after the change, and inside MacPorts only, the USRP
port will be the only port to -require- the libusb-legacy port.
2) All versions of LIBUSB (1.0, compat, legacy) install a PKGCONFIG
file that describes the necessary LDFLAGS, CFLAGS, and so forth for
compiling and linking -- in my experience, all modern MAKE variants
(qmake, cmake, autotools) either directly check for PKGCONFIG files
or easily allow for their use & hence I'd like to think that nobody
hard-wires these external libraries any longer. My proposed change
will be reflected in the installed PKGCONFIG file for libusb-legacy,
so relinking your external-to-MacPorts project should be just a
matter of re-configuring and re-building.
[*] "same name different directory" library link issue
---
Suppose we have the libraries:
1) "libfoo" is installed with FOO_LDFLAGS="-L${prefix}/lib -lfoo";
2) "libusb-compat" is installed with LIBUSB_COMPAT_LDFLAGS="-L$
{prefix}/lib -lusb";
3) "libusb-legacy" is installed with LIBUSB_LEGACY_LDFLAGS="-L$
{prefix}/lib/libusb-legacy -lusb";
then what is the linking result from:
gcc -o foo foo.o ${FOO_LDFLAGS} ${LIBUSB_LEGACY_LDFLAGS}
(assuming that the commands and files exist and are otherwise
valid)? Expanding this command out I get:
gcc -o foo foo.o -L${prefix}/lib -lfoo -L${prefix}/lib/libusb-legacy
-lusb
and since GCC works by searching the -L paths in the order
presented, "-lusb" will be found in ${prefix}/lib, not in my desired
${prefix}/lib/libusb-legacy. Hence, I need to do one of:
Wouldn't adding your desired flags to the front of configure.env,
configure.pre_args or where ever else needed work?
// Brad
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